“In extremely trying conditions they [volunteers] worked tirelessly to provide subcutaneous fluids to the pups that could be reached and many lives were saved. But sadly many lives were lost too,” said a spokesman.

“Hundreds of mainly young flying-foxes were lost to the heat. The final count could run to thousands.”

The animals died in their hundreds, possibly thousands, despite volunteers being able to save many. Picture: Facebook/Help Save the Wildlife and Bushlands in CampbelltownSource:Facebook

“It affects their brain — their brain just fries and they become incoherent. It would be like standing in the middle of a sandpit with no shade.”

The flying fox, Australia’s largest bat, is listed as a “vulnerable” species nationally with its survival ranked as a “critical priority” under local laws.

“Heat stress sadly claimed the lives of many hundreds of young flying-foxes at Campbelltown yesterday afternoon and the camp at Parramatta Park was also impacted. Without the commitment of such a dedicated team of WIRES volunteers there is no doubt the death toll would have been much higher,” a Facebook post from WIRES read.

The volunteers worked desperately as Sydney’s power and public transport infrastructure went into meltdown as a result of the record-breaking heatwave on Sunday.

In an emotional Facebook post, Help Save the Wildlife and Bushlands in Campbelltown said bats were dead on the ground, and hanging in trees.

“So many little lives lost due to the extreme heat and not enough canopy cover to shade them or keep them cool,” the post said.

“Adults sought out shade and more shelter further up the creek, resulting in many babies being left behind to deal with the heat.

“Many pups were on their last lot of breaths before getting much needed help by the WIRES members.

Heat-stricken: The dead animals fell from their trees. Picture: Facebook/Help Save the Wildlife and Bushlands in CampbelltownSource:Facebook

“As the dead bodies were recovered and placed in a pile for a headcount the numbers had reached 200 not including the many hundreds that were still left in trees being unreachable, sadly a few adults were also included in the body count.

“It was a long and heartbreaking afternoon.”

Temperature records tumbled when the Western Sydney suburb of Penrith hit 47.3C at 3.25pm Sunday, edging past its previous record of 47C on February 11 last year.

The Bureau of Meteorology initially announced Penrith’s temperature as the hottest in Sydney’s history but later clarified to say that Richmond, which reached a top of 46.3C yesterday, still held that record high. The Old Richmond Station set the record with 47.8C in 1939.